Cast iron tappet and method of making same



Oct. 19, 1937. J. l.. Dos'rAL 2,096,092,

CAST IRON TAPPET AND METHOD OF MAKING SAME- Filed July 29, 1935 Ja ser 50S iai.

ATTORNEYS.

Patented 0t.19,1937 f CAST IRON 2,096,092 Y TAPPET AND METHOD oF MAKmGsAMn.

Joseph; L. Dostal, Birmingham, Mich., assignor,' by Vmesne. assignments, to Eaton Manufacturing'Company, Cleveland, Ohio, a Vcorporation of omo' Application July 29, 1935, serial No. 33,118

(c1. 13s-9o) Y 5 Claims.

This invention relates to tappets for internal combustionV engines and more especially to the barrel type tappet composed of chilled cast iron and to the method of making and heat treating such tappet. Y

'I'he above type oftappet is preferably made by casting in apermanent molding machine provided with cooled mold sections for obtaining ,the desired hardness of the tappet parts byproperly chilling the bearing surfaces of the tappet while casting the same and then quick annealing the top end portion of the tappet so as to render such portion more easily m'achinable, thus facilitating drilling and tapping such end portion for the reception of adjusting means. l

The principal object of the invention is to improve the art of tappet constructions.

A further object is to provide a barrel type tappet of cast iron chilled completely through the peripheral walls thereof to obtain the desired hardness. Y f

It is also an object of the inventionv to provide a tappet of the above character in which the top portion has been'rendered more easily machinable than the remaining uportions of the tappet so that thetop end portion may more readily be drilled and tapped fo-r the reception of tappet adjusting means. Y

A further object is to provide `an improved method of constructing the above type of tappet.

Another object is to provide a tappet construction composed entirely of chilled cast iron except for the top or adjusting element receiving portion thereof whichjis of grey cast iron.

A further object of the invention isto provide an improved method of quick annealing anadjusting element receiving end portion of a tappet.

For the purpose of illustrating the genus Yof the invention and methods employed in effecting such invention, a typical concrete embodiment of tappet constructions and apparatus employed in making vthe same is shown in the accompanying drawing, in which: v

Figure 1 is a fragmentary top plan of a portion of a permanent molding machine employed in fabricating a tappet according to the principles of this invention; y n u Fig. 2 is a fragmentary vertical section, on an .enlarged scale, taken substantially `on vthe line 2--2 of Fig. 1; v Y Y Fig. 3 is a further enlargedcentral vertical section of a tappet formed bythe apparatus shown in Figs 1 and 2;l fr 'I Y Fig. 4 is afragmentary View, similar-to Fig. 3, but showing the tappet in an inverted position and over the flame of an open burner in'order to l depict a step in the heat treatmentto which the tappet is subjected; and

. Fig. 5 is a fragmentary central vertical section illustrative of the condition of theitappet after being subjected to the above indicated heat treatment step and after being machined andequipped with adjusting means.

Tappfets are preferably 22 adapted to communicate with a suitablesource f of suction, not shown, for drawing-cooling air through themolds I2. Openings 23extcnd downwardly through the base portion vof the stationary mold carrier I4 to provide..communicatiorn,loe--ly constructedaccordi'fig. to the principles of this inventionl bymeans Aof af tween the suction chamber 22 andthe-interior Y of a trough-like partial annulus 24 openjatthe bottom and communicating with theinteriorof f" plurality of headers 25. The headers 2,5ieach carries a number of support members 2Q fory each of the pivots I8. Bolts 21 extending through elongated openings 28 permit the vsupporty2l for pivots lI8 to be connected vtothe headers 425'and, adjusted so as properly to align the swingable-moldcarriers I6 with respect to the'stationary moldqar-v rier I4. The pivot support members 26 also -carryupstanding guide membersSI each having-a forked upper end 32 v-for guiding` andbracing as -fwell as limiting the outward. swinging movement of the movable mold carriers I6. The swingable mold carriers I6 are each provided with a passage 33 extending froma mold I2 tothe interior cf-a pivot support element 26,which communicates with the interior of a header element ,25. The lower ends of the passages 33 terminate in conduits 34 curved about the axis ofla pvot pin I8 as a center and' proj ecting through suitableopen-V ingsV tothe interior ofa pivot 'support' element 26. Cooling air is'thus'drawn throughtlfie1 molds I2, through ypassages 33 A andcurvedconduits,34,.

through the interiorsof pivot support elements v26, yheaders 25 and theannulus 24-, and?- through the openings 23 to the' suctionfchamber 22'by f the suction producing means, not shown;

I The molds IZ'are adapted Vtoibo maintained"inV vided adjacent the upper end of the swingableg l mold carriers l 6. 'Ihe pressure exerted by springs 40 forvmaintaining the swiigable'mldcarriers" i6 in closed condition is prevented from Vcal'ising a lateral thrust upon the, shaft2 0 byte support member 42 including a bearing 43`witliinlwhich the shaft is journaled, a pair ofxracliallyA extending arms 44 and a bridge member 45 upon which the holder 38v is secured. The support Ymember ,4,2

also has xed thereto a roller carrier l1 Which-V pivotally supports a series of rollers 48-arranged` on an arc of a circle having the axisof shaft "direction, asli/liewed in 1, causes' Fthe cam :icontacts4l oleachof tlrievs'win'gable moldcarriers I6 successively to engag a closing cam V50 fsoe'thatjthe' glatter"swingsftheimold carriers I6 '30 inwardly'toward the "shaft 20`to close the' molds Y allow 'fthe rollers "35, and springs' 3 1 'to mairi- Et nfthe'molds 'inclosed condition under spring "prssure'fTh cam contacts are beveledoutwaridly""oni'ythe inneraceV Vthereof asindic'ated "earn*52ibeyond'the seriesof' rollers-35jto cause opening `of the `moldsfas the cam`52 causes Voutward'fswingingf of inold'ca'rriers "I.6.` The cams and -52V are supportedV byorrin xed relation A'iRefer'ring'--fmore especially toFig.l2`, the molds 'l f2 fare illus'trated comprisingmanL-moldl sectio Glland (ilVY separable with'nteference'toa v'rticalfparting line62. lTle main lmold sections N145 are aohfprovidediwithl a substantially semi-.cylindrical ml'dfc'avity 63,` reduced in'- size iatf one end fand'ad'aptedtorAcoperatewith the mold Ycavity of fh'eother main moldsectionitoform .'atappet 65 N ff vi',he^g'er1eraloutline-indicated inFigsl'S, 4,1and 5015( A separate mold 1sectionf64, substantiallypin fthe form of afhollow piston Aolosed'at 'its upper v`'en'd--f` and provided with a cooling n;.66V integral withY such closed end and extending q downwardly withinthe interior of'the'ipiston, ,isiadapted to A602y piraiity of Euch openings maybe: provided in the separate Y section I64 Vto eilect' de'sired 1 variations the length ofthe tappets produced.' Thei'sep- VaAr'ater section 64,which formsthe cam-'engaging end ofitappetz65 is'hollowzto form'anairpassage cfror the animation of coonmgfair Vtherenlroug11 and "the'length of` this .separatelsection `is tmade j severaltimes its diameterin: orderto increase the rea '.ofjcontactjof'thefseparate'.section with' the v.low'..pistonelike separatemldsections 6d :and

M.viding'a pin which extends inwardly from one of the projections formed in the mold impression 10 fand cooperatesgwith a suitable opening arranged in ajpredetermined position in the core 679. n

' The following analysis ofY iron has been found particularly ysuitableV for 'producing an all chilled s tappet; Carbo`n12l75 to 3.50 percent, silicon 1.70 15 to 2.60 percent,.manganese 0.40 to 1.10 percent, phosphorus 0,'20 to 0.30 percent, sulphur 0.115 ipercen't, .andthe 'balance iron.

,jllhemain mold` sections and 6| and the separate bottom section 64 are all composed of metal 20 sothat all" partsof thertappetsproducedzwill be `g chilled entirely through-the walls thereofY as long as 'ithe rriai'nandA separatejsections ofthe mold 1j are :kept Vinia sufficiently icoolcon'dition. Y

The cooling of the mold I2 is eiected by pro- 25 vidinghollowed yout' cavitiesj ln the 'backs' of the main moldsections 60 and-6glpwhich cavities, in Y :conjunction with thefstationary andswingable mold section ucarriers-:114and I 6,l provideicooling :passages '10. ."'Ihe cooling vpassages -107` of .the e30 'Y lswingable mold sections '60 communicate at lits -lower'ends with the passages 33 to the swingable mold carriersl'6 so asto exhaust airthrough the llatterfat al1 timesregardlessof'whether'the molds l2 are in open or closed condition; Cooling ain-335 is i admitted Ito v the passages 10 Yof A:the swingable main mold-'sectionslthrough'openings 1ly andYY lzgprovided in the'swingablamold carriers. The i air inletpassages 12V-lead directlyinto-the cooling ,L passages10 whilethe air. in rthepassages 1| lead@ through hollowed out spaces 13 provided in each vblock of-pairs of vpouring blocks `14 vseparable along the ixpar'ting .line f 62vnand constituting two piece pouringebasinf at rthef1201) rOfgthe mold. vAir `is .ad-

fmitted'rat alltimes-ltolthe.- cooling .passages 10 of.` 43

the .stationary mainVA mold section 56| :through air linlet passages 15 andw16 lprox/'idedcthrough `the stationary mold carrier |4, theinlet passages 16 vleadingldirectlyrto the cooling passages 10 while fthe air inlet passages '15,communica'te through` 0 V,passages.13fin= then other .pouring-blocks 14 an'd 0 then to the .cooling passages1-0. Airis exhausted fromthe cooling passages 10 vof the-.stationary main mold sections 6I through Vpassages '11n-lead# ingrirectly from the coolingf .passages L10 Eto the` 'suction chamber .22- of thecooling-system.v l The pouring blocks 14 .areprovidedcentrally kwith cog operable lrecessesfforming` a Vgatej1Y adapted to serve .as a sprueand gatefor.pouringiithencasting. Air isradmittedfthrough'the openlends of the holdrawn` .upwardly so as to ,wipethe cooling ns- 66 and then through passages 80 provided`through the walls of .the..separate mold sectionsgand through the stationary mold sections v6l @tojthew cooling V.passages 1U thereof,.andthen exhausted-l o through' the passages 11 to lthesuctioncrhamber n Y22 of thecoolingsystem.l .Themoldpsurfaces'of L l,the main mold Ysections 60 andf l Vare preferably "treated wana, thin refratory facingland scopedV -inr the manner disclosedin the vMaloche! Patents 1,453,593 and 11,492,694. Y Y ,l

Reference may now be had to Figure 3, which disclosesggthe tappet as formedl bythe casting apparatus; illustrated y-in Figures A1y `and Y, 2. {Ilia-75 toA tappet65 comprises a cylindrical body portion 8| having an integral end closure 82 constituting the Y cam-engaging end of the tappet and an integral end closure 83 constituting the head end which may, if desired, be drilled and threaded to constitute the adjustment receiving end of the tappet. As previously indicated, the tappet is provided with windows 68 for the purpose of lightening the tappet, permitting circulation of air through the interior of the tappet, and for clearing the interior of the tappet of oil which may be forced therein. To clear the tappet of oil, the windows 68 are provided with outwardly beveled margins as indicated in Figure 3, which will tend to cause a radially outward movement of oil or oil vapor contained within the interior of the tappet and will trap oil at the bottom margins of the windows so as to lubricate the periphery of the tappet and the bore of the tappet guide, as well as permitting a certain amount of oil to drip from the packets at the bottom margins of the windows and follow the outside surface of the tappet to lubricate the cam engaging end thereof. The cylindrical portion 8 of tappetV 65 and the cam engaging portion 82 are of comparatively thin metal sections and since they are formed by casting Ywithin a cooled vmetal mold, these metal sections will be chilled completely through to the hollow interior of the tappet. The tappet composed of the iron of the analysis above described will be hardened upon chilling as it is cast so that the tappet will have the desired hardness and wearing qualities to adapt it for the purpose intended. The separate section E4 of the mold, due to the extensive interior surface area and the area of the cooling iin 56, all of which areas are wiped by the cooling air, or other vdesired cooling medium, receives a somewhat greater chill and is hardened to a greater extent than the peripheral wall portion 8|. The end closure 83 also receives a chillA since this is in contact with the metal of the main mold sections 60 and 6l and receives a sufcient hardness so that it is rather difficult to machine. When a non-adjustable tappet is desired, finish grinding of tappe-t 65 remains to be done.

Where an adjustable tappet is desired, the tappet, after casting and cooling, has the end closure 83Yreheated and annealed to render the same more machinable. As indicated in Fig. 4, the tappet 65 has the endrclosure `83 thereof exposed directly to the flame of an open burner 85 until the end closure 83 is heated to an annealing temperature of from 1670 to 1700 degrees Fahrenheit, and then the tappet 65 is allowed to cool in air. The temperature to which the top portion 83 of the tappet is heated lies within the critical range of temperatures of iron of the composition above indicated so that when allowed to cool in the air, the topportion has its hardness reduced so that it may be readily machined.

Referring to Figure 5, the top portion 83 of the tappet is then drilled and threaded as indicated at 86 for the reception of a threaded adjusting element 81 adapted to be secured in adjusted position by means of a lock nut B8. The exterior sur- Vsented by the nished tappet.

' all bearing portions of the tappet.

faces of the tappet 65 may then be finished ground to the dimensions desired. Since all bearing portions of the tappet 65 have been chilledY completely through to the hollow interior of the tappet, the grinding operation does not matec rially change the hardness of the surface pretory and soot facings of the mold cavities prevent too rapid cooling of the exterior surface of the tappet so that the peripheral walls and cam-engaging portion of the tappet will cool more uniformly, but with suicient rapidity due tothe cooling ofthe mold sections so that the desired hardness of metal will be obtained throughout The quick annealing of the top portion 83 of the-tappet, when an adjusted tappet is to be formed, as indicated The thin refrac- I in Fig. 4, converts the chilled cast iron to softer or grey cast iron, the major portion of the latter being removed in drilling the bore 8B, so that the completed tappet with the exception of the threaded walls of the bore 86 is of chilled cast iron. The softer iron portion is indicated in Figs. 4 and 5 by wider spaced section lines. Y

As many changes could be made in the above constructioncand methods, and many apparently widely different embodiments of this invention could be had without departing from the spirit thereof, it is intended that all matter shown in the accompanying drawing and contained in the above description is to be interpreted as illustrative and not in a limiting sense.

What is claimed is: Y

1. A hollow-cast tappet for internal combustion engines comprising a hollow cylindrical body having relatively thin peripheral wall portions composed entirely of chilled iron.

2. A hollow-cast tappet for internal combustion Y engines comprising a hollow cylindrical body including an integral end closure, said body and end closure being of Yrelatively thin metal vsections composed entirely of chilled iron.

3. A hollow-cast tappet for internal combustion engines comprising a hollow cylindrical body including parts adapted to make bearing engagement with a valve guide and a valve Voperating element, all of said bearing portions of the `tappet being composed of chilled iron.

4. A hollow-cast tappet for internal combustion engines comprising a hollow cylindrical body having relatively thin peripheral wall portions..V

composed entirely of chilled iron and an end 

